The present invention relates to control systems and pertains particularly to combined brake and creeper control systems for industrial vehicles.
Many industrial trucks, such as lift trucks and the like, are powered by gasoline engines and include a hydrostatic transmission for transmitting power from the engine of the vehicle to the driving wheels thereof. The hydrostatic transmission employs a hydrostatic motor and pump and is controlled by varying the displacement of one or the other, or both, of the motor and pump to achieve forward and reverse of the vehicle and to control speed thereof.
Because of the limit on the number of manual control members that an operator can successfully manipulate for control of the vehicle, many functions of the vehicle are combined to single manual control members. For example, the drive and transmission control are normally combined in a single element. A separate brake control pedal and a separate creeper control pedal are also normally provided. The creeper control functions to override the normal transmission control valve to permit the engine R.P.M. to be raised for fast lift of a load while the vehicle is traveling slowly or not at all. Such manipulation, however, is difficult if not impossible to accomplish on a hill or other slope because the transmission must be disabled and the brakes applied simultaneously, or to secure the vehicle while loading or unloading and still maintain maximum engine speed for lifting.